Performing inter-frequency measurements in a mobile network

ABSTRACT

Methods, apparatus and articles of manufacture for performing inter-frequency measurements in a mobile network are disclosed. An example method in a mobile station disclosed herein comprises receiving, from a network, a list specifying a set of frequencies for which measurements are to be performed, and if the set of frequencies exceeds a monitoring capability of the mobile station, prioritizing measurement of a subset of frequencies from the set of frequencies based on information separate from the list obtained from the network.

FIELD OF THE DISCLOSURE

This disclosure relates generally to mobile networks and, moreparticularly, to performing inter-frequency measurements in a mobilenetwork.

BACKGROUND

In many mobile networks, the mobile network sends neighbor cellinformation to mobile stations operating in the network to indicateneighbor cells for which measurements are to be performed. The neighborcell information may list cells having different carrier frequencies.Additionally, in a mobile network supporting multiple radio accesstechnologies (RATs), such as universal terrestrial radio access network(UTRAN) functionality and GPRS EDGE radio access network (GERAN)functionality, the neighbor cell information may list cellscorresponding to different RATs, as well as different carrierfrequencies. (GPRS refers to the general packet radio service, EDGErefers to enhanced data rates for GSM evolution, and GSM refers to theglobal system for mobile communication.) As such, the neighbor cellinformation sent by such mobile networks may indicate that the mobilestation is expected to perform inter-frequency measurements across oneor more RATs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is block diagram of an example mobile network in whichinter-frequency measurements can be performed as disclosed herein.

FIG. 2 is a block diagram of an example mobile station and an examplenetwork element that can be used to implement the example mobile networkof FIG. 1.

FIG. 3 is a block diagram of an example implementation of at least aportion of the example mobile station of FIG. 2.

FIG. 4 illustrates an example path followed by the example mobilestation of FIG. 2.

FIG. 5 is a block diagram of an example implementation of at least aportion of the example network element of FIG. 2.

FIG. 6 is a flowchart representative of an example process that may beperformed to implement the example mobile station of FIG. 1, 2 and/or 3.

FIG. 7 is a flowchart representative of an example process formeasurement scheduling that may be used to implement the example processof FIG. 6 and/or that may be executed to implement the example mobilestation of FIG. 1, 2 and/or 3.

FIG. 8 is a flowchart representative of an example process for frequencyprioritization that may be used to implement the example process of FIG.6 and/or that may be executed to implement the example mobile station ofFIG. 1, 2 and/or 3.

FIG. 9 is a flowchart representative of an example process for neighborprioritization that may be used to implement the example process of FIG.6 and/or that may be executed to implement the example mobile station ofFIG. 1, 2 and/or 3.

FIG. 10 is a flowchart representative of an example process for receivedsignal strength indication measurement that may be used to implement theexample process of FIG. 6 and/or that may be executed to implement theexample mobile station of FIG. 1, 2 and/or 3.

FIG. 11 is a flowchart representative of an example process forreselection prioritization that may be used to implement the exampleprocess of FIG. 6 and/or that may be executed to implement the examplemobile station of FIG. 1, 2 and/or 3.

FIG. 12A is a flowchart representative of an example process formeasurement limitation signaling that may be used to implement theexample process of FIG. 6 and/or that may be executed to implement theexample mobile station of FIG. 1, 2 and/or 3.

FIG. 12B is a flowchart representative of an example process formeasurement configuration based on information received from the exampleprocess of FIG. 12A and that may be used to implement the examplenetwork element of FIG. 2 and/or 5.

FIG. 13 is a flowchart representative of an example process forfrequency selection that may be used to implement the example process ofFIG. 6 and/or that may be executed to implement the example mobilestation of FIG. 1, 2 and/or 3.

FIG. 14 is a flowchart representative of an example process for macrocell prioritization that may be used to implement the example process ofFIG. 6 and/or that may be executed to implement the example mobilestation of FIG. 1, 2 and/or 3.

FIG. 15 is a block diagram of an example processing system that mayexecute example machine readable instructions used to implement one ormore of the processes of FIGS. 6-13 and/or 14 to implement the examplemobile network of FIG. 1, the example mobile station of FIG. 1, 2 and/or3, and/or the example network element of FIG. 2 and/or 5.

DETAILED DESCRIPTION

Methods, apparatus and articles of manufacture for performinginter-frequency measurements (e.g., across one or more RATs) in a mobilenetwork are disclosed herein. In an example method disclosed herein, anexample mobile station obtains, from an example network, a listspecifying a set of frequencies for which measurements are to beperformed. For example, the list may correspond to a neighbor cell listspecifying third generation (3G) cells, such as UTRAN cells, and/orsecond generation (2G) cells, such as GERAN cells. In the examplemethod, if the set of frequencies specified in the list exceeds amonitoring capability of the mobile station, the mobile stationprioritizes measurement of a subset of frequencies from the set offrequencies based on information separate from the list obtained fromthe network.

For example, the information separate from the list obtained from thenetwork can include a list of prior frequencies used by the mobilestation. For example, the list of prior frequencies can be maintained bythe mobile station and contain frequencies of a set of cells with whichthe mobile station has been in a connected state or on which the mobilestation has been camped. However, in some examples, the list of priorfrequencies may exclude each cell on which the mobile station has beencamped in a limited service state. In such an example, the mobilestation can prioritize measurement of the subset of frequencies bydetermining the subset of frequencies to be those frequencies includedin both the list obtained from the network and the list of priorfrequencies used by the mobile station. In some examples, if measurementof the determined subset of frequencies does not yet exceed themonitoring capability of the mobile station, the mobile station canperform measurements for this subset of frequencies and another subsetof frequencies in which each frequency in this second subset offrequencies is selected from the set of frequencies based on, forexample, a number of cells associated with the frequency, a receivedsignal strength indication associated with the frequency, etc.

In another example, the information separate from the list obtained fromthe network can include received signal strength indication measurementsobtained for each frequency in the set of frequencies. In such anexample, the mobile station can prioritize measurement of the subset offrequencies by determining the subset of frequencies to include a numberof frequencies having the highest received signal strength indicationmeasurements.

In yet another example, the information separate from the list obtainedfrom the network can include a respective reselection priority obtainedfor each frequency in the set of frequencies. In such an example, themobile station can prioritize measurement of the subset of frequenciesby determining the subset of frequencies based on the reselectionpriorities.

In a further example, the mobile station can prioritize measurement ofthe subset of frequencies by determining the subset of frequencies toinclude a first subset of frequencies appearing at the beginning of thelist obtained from the network and a second subset of frequenciesdetermined based on the information separate from the list obtained fromthe network. Other examples and combinations of examples for performinginter-frequency measurements in a mobile network are described ingreater detail below.

As mentioned above, mobile networks can send neighbor cell informationto mobile stations operating in the network that indicates the mobilestations are expected to perform inter-frequency measurements across oneor more RATs. For example, the inter-frequency measurements that themobile station is expected to perform may include measurements on one ormore other frequencies of the same RAT in which the mobile station iscurrently operating. Additionally or alternatively, the inter-frequencymeasurements that the mobile station is expected to perform may includemeasurements on one or more frequencies of one or more other RATsdifferent from the RAT in which the mobile station is currentlyoperating. Thus, as used herein, the term inter-frequency measurementscan refer to measurements to be performed on one or more otherfrequencies of the same RAT in which the mobile station is currentlyoperating, and can also refer to measurements to be performed on one ormore frequencies of one or more other RATs different from the RAT inwhich the mobile station is currently operating.

In some scenarios, the number of frequencies (across one or more RATs)specified in a signaled neighbor cell list can exceed the monitoringcapabilities of a particular mobile station. Mobile station behavior inprior mobile networks that are compliant with the Third GenerationPartnership Project (3GPP) specifications, such as prior networkssupporting UTRAN and/or GERAN functionality, is not specified for casesin which the number of frequencies (across one or more RATs) specifiedin the signaled neighbor cell list exceeds the mobile station'smonitoring capabilities. Therefore, in such cases, these prior mobilenetworks may not know for which frequencies a mobile station willperform and report measurements. Unlike such prior networks, in theexample mobile networks disclosed herein, mobile station behavior isspecified for situations in which the number of frequencies (across oneor more RATs) specified in the signaled neighbor cell list exceeds themobile station's monitoring capabilities. Furthermore, exampleapproaches for prioritizing inter-frequency measurements when the numberof neighbor cell frequencies (across one or more RATs) exceeds themobile station's monitoring capabilities are disclosed.

Turning to the figures, FIG. 1 illustrates a block diagram of an examplemobile network 100 in which inter-frequency measurements can beperformed as disclosed herein. The mobile network 100 illustrated inFIG. 1 includes GERAN (or, more generally, 2G) cells 105A-C and UTRAN(or, more generally, 3G) cells 110A-C and 115A-C. The UTRAN cells 110A-Cand 115A-C in the illustrated example correspond to UTRAN macro-cellsdeployed on two different UTRAN carrier frequencies, denoted as F1 andF2 in FIG. 1. In the illustrated example, the mobile network 100 alsoincludes UTRAN (or, more generally, 3G) femto cells 120A-C, which aredeployed to operate on a further UTRAN carrier frequency, denoted as F3in FIG. 1. In some examples, the mobile network 100 can include one ormore Evolved-UTRAN (E-UTRAN) cells (not shown) deployed on one or moreE-UTRAN carrier frequencies and/or one or more cells (not shown) of oneor more other RATs deployed on one or more carrier frequencies of thoseother RAT(s).

The mobile network 100 illustrated in the example of FIG. 1 alsoincludes an example mobile station 125, also referred to herein as userequipment (UE) 125. In the illustrated example, the mobile station 125is multi-RAT capable and can communicate with and/or performmeasurements of the GERAN cells 105A-C, the UTRAN cells 110A-C and115A-C, and the femto cells 120A-C. Furthermore, and as described ingreater detail below, the mobile station 125 can implement one or moreof the example techniques for performing inter-frequency measurementsdisclosed herein. Additionally, in some examples, one or more networkelements implementing the GERAN cells 105A-C, the UTRAN cells 110A-Cand/or 115A-C, and/or the femto cells 120A-C can support one or more ofthe example techniques for performing inter-frequency measurementsdisclosed herein. Although the mobile station 125 is depicted in FIG. 1as being multi-RAT capable, in some examples the mobile station 125could support just a single RAT, such as UTRAN, and implement one ormore of the example disclosed inter-frequency measurement techniques toperform inter-frequency measurements on multiple frequencies in thesingle RAT supported by the mobile station 125. Also, although theexample mobile network 100 includes three GERAN cells 105A-C, six UTRANcells 110A-C and 115A-C, three femto cells 120A-C, and one mobilestation 125, the example inter-frequency measurement techniquesdisclosed herein can be used in a mobile network including any number ofGERAN cells 105A-C, UTRAN cells 110A-C and/or 115A-C, and/or femto cells120A-C. Moreover, the example inter-frequency measurement techniquesdisclosed herein are not limited to mobile networks employing GERAN,UTRAN and femto cells as illustrated in the example of FIG. 1, but maybe used in any mobile network in which mobile stations may be directedto perform measurements on multiple frequencies such that themeasurement or monitoring capabilities of a mobile station may beexceeded. For example, the inter-frequency measurement techniquesdisclosed herein can be used in a Long Term Evolution (LTE) networksupporting E-UTRAN cells in addition or as an alternative to the GERAN,UTRAN and/or femto cells illustrated in FIG. 1.

Inter-frequency measurements are performed by a mobile station, such asthe mobile station 125, to support UE mobility in a mobile network, suchas mobility between the GERAN cells 105A-C, the UTRAN cells 110A-Cand/or 115A-C, and/or the femto cells 120A-C of mobile network 100. UEmobility within the mobile network 100 may be either UE controlled ornetwork controlled. In the context of the UTRAN portion(s) of the mobilenetwork 100, UE controlled mobility is used in Idle mode and in theCELL_PCH, URA_PCH and CELL_FACH states of RRC Connected mode. Networkcontrolled mobility, on the other hand, is used by the mobile network100 in the CELL_DCH state of RRC Connected mode. In the context of theGERAN portion(s) of the mobile network 100, UE controlled mobility isused in Idle mode, whereas network controlled mobility is used inDedicated mode. Furthermore, either UE or network controlled mobilitymay be used in Packet Transfer mode or Packet Idle mode, where theselatter two states are applicable if the mobile station 125 is attachedfor GPRS services.

In the context of UE controlled mobility, the mobile station 125 choosesa serving cell on which to camp via a process of cell selection andreselection. Cell selection is the process via which the mobile station125 can choose a serving cell when the mobile station 125 does notcurrently have a serving cell. For example, the mobile station 125 maynot have a serving cell when the mobile station 125 is initiallyswitched on, or when the mobile station 125 is returning from a loss ofnetwork coverage, etc. Cell reselection is the process by which themobile station 125 changes from one serving cell to another servingcell. Typically the cell reselection process involves the mobile station125 evaluating the signal strength and/or signal quality of the servingcell and a number of candidate neighbor cells. The mobile station 125can then reselect to one of the neighbor cells that is determined tomeet certain criteria based on the foregoing measurements and otherparameters, such as hysteresis (which may be standardized and/orsignaled by the mobile network 100).

The mobile network 100 guides or assists UE controlled cell selectionand reselection by providing control information to the mobile station125 in broadcast system information messages. The information mayinclude neighbor cell lists to identify the RAT, carrier frequency and,possibly, identity of candidate neighbor cells for cell reselection. Theinformation may also include various offsets, thresholds and/or otherparameters to allow the mobile network 100 to affect the cellreselection behavior of the mobile station 125. In a UTRAN cell, such asone of the UTRAN cells 110A-C or 115A-C, broadcast System Information(SI) Block Type 3, 4, 11, 11bis, 12 and/or 19 messages may containinformation related to cell reselection. In a GERAN cell, such as one ofthe GERAN cells 105A-C, various system information messages, includingSystem Information (SI) Type 2 quater (SI-2 quater) messages, maycontain information related to cell reselection.

The mobile network 100 may additionally or alternatively provideUE-specific control information in dedicated messages (i.e.non-broadcast messages) sent to mobile station(s), such as the mobilestation 125, in one or more of the cells 105A-C, 110A-C, 115A-C and/or120A-C. For example, in the context of the UTRAN portions of thenetwork, the mobile network 100 may send a UTRAN MOBILITY INFORMATIONmessage including dedicated priority information that controls therelative priority of cells using different carrier frequencies and/ordifferent radio access technologies. This message may be sent to themobile station 125 in the CELL_FACH or CELL_DCH states, and thededicated priority information provided in the message may besubsequently used to affect how the mobile station 125 performs cellreselection in the CELL_FACH, CELL_PCH and/or URA_PCH states, and/or inidle mode. In the context of the GERAN portions of the network, themobile network 100 may send messages, such as Measurement Information(in dedicated mode) or Packet Measurement Order (in packet transfer modeor packet idle mode), as dedicated messages to mobile station(s), suchas the mobile station 125, to allow UE-specific parameters to be sent tothese mobile station(s).

In the context of network controlled mobility, the mobile network 100chooses which cell (or cells) are to be used to communicate with themobile station 125 or, in other words, is (are) to be the servingcell(s) for the mobile station 125. The network decision is typicallyassisted by radio measurements performed by the mobile station 125 forits current serving cell(s) and also for a number of candidate neighborcells, which are reported to the mobile network 100. The mobile network100 may provide the mobile station 125 with relevant informationincluding, for example, one or more neighbor cell lists that identifythe RAT, carrier frequency and, possibly, identity of candidate neighborcells. Additionally or alternatively, the information may includevarious offsets, thresholds and/or other parameters to allow the mobilenetwork 100 to configure the measurement reporting behavior of themobile station 125. In a UTRAN cell, such as one of the UTRAN cells110A-C or 115A-C, this information may be sent to the mobile station 125in a dedicated manner in a Measurement Control message, and/or may bebroadcast in System Information (SI) Block Type 11/12 messages. In aGERAN cell, such as one of the GERAN cells 105A-C, this information maybe sent to the mobile station 125 in a dedicated manner in a PacketMeasurement Order or a Measurement Information message, and/or may bebroadcast in, for example, an SI2quater message.

The femto cells 120A-C, also referred to as home basestations or homeNode-Bs, are generally smaller, lower power basestations that connectinto the operator's network 100, but may be owned by the user and placedby the user within a home, office, etc. The femto cells 120A-C canimprove radio coverage or system capacity in a location in which theoperator's network 100 may provide poor or non-existent coverage. Insome examples, the owner of a femto cell 120A-C and/or the networkoperator has control over which mobile stations, such as the mobilestation 125, are permitted to obtain service via the femto cell, withother users being denied access. In at least some deployments of 3G orUTRAN femto cells, such as the femto cells 120A-C, the operatorconfigures the femto cells to operate on carrier frequencies differentfrom those used by the operator's macro cell network, which correspondsto the macro cells 105A-C, 110A-C and 115A-C illustrated in the exampleof FIG. 1. Additionally, the operator's macro 2G and 3G cells (e.g., themacro cells 105A-C, 110A-C and 115A-C in the example of FIG. 1), areconfigured to list the femto cells frequency (and/or their frequencies)in broadcast system information.

For 3GPP Release 8 and later releases, the 3GPP specificationsintroduced closed subscriber group (CSG) functionality to improve andstandardize operation of femto cells. As part of this functionality, amobile station, such as the mobile station 125, supporting CSG is to beable to find a CSG cell that it has previously accessed without any RAT,frequency, or identity information of the CSG cell being provided by theoperator's macro cell network. Instead, such a mobile station is toperform an implementation-specific autonomous search function to findthe CSG cell. However, such functionality is generally limited to newermobile stations. To enable femto cells to be used by legacy mobilestation that do not support the autonomous search functionality, and toenable mobile stations that support CSG to efficiently locate CSG cellsin general, operators may include information relating to such cells(such as the femto cell frequency or frequencies, physical layeridentity ranges, etc.) in broadcast system information.

The example inter-frequency measurement techniques disclosed herein canenable the mobile station 125 to determine for which frequencies (andcells) measurements are to be performed when the mobile network 100provides measurement configuration information (e.g., such as one ormore neighbor cell lists) that exceeds the monitoring capabilities ofthe mobile station 125. For example, in inter-system (e.g., 2G&3G)deployment scenarios, network operators can configure neighbor cellslists to request a multi-RAT mobile station, such as the mobile station125, to measure many UTRAN/3G frequencies from a GERAN/2G cell. However,according to Section 6.6.4 (relating to idle mode measurements) andSection 7.3 (for measurements during dedicated mode) of 3GPP TechnicalSpecification (TS) 45.008, Radio Subsystem Link Control, v10.0.0, March2011, which is incorporated by reference in its entirety, a multi-RATmobile station shall be able to monitor cells from UTRAN on up to three(3) frequency division duplex (FDD) frequencies and on up to three (3)time division duplex (TDD) frequencies. Under the existing 3GPPspecifications, mobile station behavior is not specified if the numberof UTRAN/3G frequencies or cells (e.g., in the 3G cell reselection list)exceeds the mobile station's monitoring capabilities as defined in 3GPPTS 45.008 (see e.g., 3GPP TS 44.018, v10.2.0, March 2011, sub-clause3.4.1.2.1.7, which is incorporated herein by reference in its entirety).As such, in some prior 3GPP-compliant networks, when a network operatorhas configured its GERAN/2G cells to list cells using more than three(3) UTRAN (FDD or TDD) frequencies, mobile stations in the network maysimply pick just the first three (3) frequencies (e.g., specified in theform of UTRA absolute radio frequency channel numbers, or UARFCNs) givenin the SI2-quarter information transmitted by the GERAN/2G network, andignore the rest of the frequencies.

Additionally, in a 3G (UTRAN) deployment, or an inter-system (e.g.,2G&3G) deployment, the signaling defined in 3GPP TS 25.331, RadioResource Control (RRC) Protocol Specification, v10.3.1, March 2011,which is incorporated herein by reference in its entirety, is flexibleand enables up to 32 UTRAN inter-frequency cells to be configured (see3GPP TS 25.331, section 10.3.7.13). In theory, all of these 32 cellscould be on different UTRAN carrier frequencies, thus allowing 32different UTRAN carrier frequencies to be deployed. However, deploymentof such a large number of UTRAN carrier frequencies is generally notpractical and, instead, the number of different UTRAN carriers actuallydeployed in a network might be two (2) or three (3). 3GPP TS 25.133,Requirements for Support of Radio Resource Management (FDD), v10.1.0,March 2011, which is incorporated by reference herein in its entirety,specifies mobile station (UE) performance requirements for measurements,cell reselection, handover, etc., when the mobile station (UE) isoperating in FDD mode. For example, section 4.2.2.8 of 3GPP TS 25.133provides that the mobile station must be capable of monitoring 32inter-frequency cells, including FDD cells on a maximum two (2)additional carriers, and if the mobile station also supports TDD mode,TDD cells distributed on up to three (3) TDD carriers. It is possiblethat a network operator could configure the system information toinclude more than two (2) inter-frequency UTRAN FDD carriers and/or morethan three (3) UTRAN TDD carriers even though a mobile station isrequired by the 3GPP specification to be able to monitor cells from justtwo (2) UTRAN FDD carriers and three (3) UTRAN TDD carriers. If thisoccurs, the existing 3GPP specifications and, in particular, 3GPP TS25.331, section 8.6.7.14, specify that the mobile station is to monitorat least the cells from the first N carriers listed in the systeminformation, but permits the mobile station to ignore all furthercarriers. The value of N is specified within the mobile station (UE)performance requirements provided in 3GPP TS 25.133.

Furthermore, 3GPP TS 25.123, Requirements for Support of Radio ResourceManagement (TDD), v10.1.0, March 2011, which is incorporated byreference herein in its entirety, specifies mobile station (UE)performance requirements for measurements, cell reselection, handover,etc., when the mobile station (UE) is operating in TDD mode. Therequirements specified in 3GPP TS 25.123 for TDD mode generally mirrorthose specified in 3GPP TS 25.133 for FDD mode. However, one differenceis that for a mobile station (UE) camped on a UTRAN TDD 1.28 mega-chipper second (Mcps) cell, the mobile station (UE) is to be able to measure32 inter-frequency cells, including TDD mode cells on up to at least 8additional TDD carriers. Thus. for operation in UTRAN TDD 1.28 Mcpsmode, the mobile station (UE) is required to measure on an increasednumber of frequencies compared to operation in FDD mode.

Table 1 summarizes of the measurement performance requirements, in termsof the number of carrier frequencies that a UE is required to measure,for different cases according to the existing 3GPP specifications.

TABLE 1 Number of frequencies UE is required to measure RAT/mode inter-inter-RAT/ of cell on Applicable RAT/mode mode TDD which UE 3GPP inter-FDD 1.28 Mcps is camped Specification frequencies frequenciesfrequencies UTRA FDD TS 25.133 2 n/a 3 UTRA TDD TS 25.123 8 3 n/a 1.28Mcps GERAN TS 45.008 n/a 3 3

The existing 3GPP specifications, and the associated measurementperformance requirements listed in Table 1, may be acceptable for priormobile networks deployed with at most three (3) UTRAN TDD carrierfrequencies and at most three (3) UTRAN FDD carrier frequencies. In suchprior networks, the network operator can configure all deployed UTRANcarrier frequencies to be listed in the system information of its 2Gcells, and mobile stations (UEs) camping on these 2G cells will havesufficient monitoring capabilities to be able to measure and reselect toany of the 3G cells on any of these UTRAN carrier frequencies.Similarly, the network operator can configure the system information ineach 3G FDD cell to list the other 2 UTRAN FDD carrier frequencies asinter-frequency carriers. This operation has been acceptable for early3G FDD deployments as network operators have generally deployed three(3) or fewer UTRAN carriers because, for example, operator have notowned spectrum licenses for more than three (3) carriers, and/or theremay not have been sufficient capacity demand to justify the deploymentof more carriers.

However, a network operator may wish deploy more than three (3) UTRANcarriers in a mobile network, such as the mobile network 100 of theillustrated example, for at least one or more of the following reasons.First, new spectrum is becoming available for 3 G operation. Theexisting 3GPP specifications define 17 UTRA FDD bands, and there isongoing work to define further bands. Operators are acquiring licensesfor spectrum in these new bands, and bands used for older radiotechnologies are also being re-farmed for 3 G operation. Second,mergers, acquisitions and RAN-sharing agreements provide opportunitiesfor operators to increase the number of available carrier bands that canbe deployed in their networks. Third, the use of femto cells generallyrequires the availability of at least one additional UTRAN carrierseparate from the carrier used for the macro cells in an operator'snetwork. Fourth, low chip rate (1.28 Mcps) UTRA TDD networks (alsoreferred to as time division synchronous code division multiple access,or TD-SCDMA, networks) use a narrower channel bandwidth of 1.6 MHz, ascompared to the 5 MHz used for UTRA FDD networks. Consequently, for agiven amount of radio spectrum, network operators can deploy more UTRANTDD carrier frequencies than UTRA FDD carrier frequencies. As describedabove, for operation within TDD 1.28 Mcps mode, the UE is expected tomeasure an increased number of frequencies as compared to operationwithin FDD mode, but this expectation is not consistent with theexisting performance requirements listed in Table 1 for a mobile station(UE) camped on a GERAN (2G) or UTRAN FDD (3G) cell and measuring UTRANTDD (3G) 1.28Mcps cells.

For mobile networks, such as a network similar to the mobile network 100but in which more than three (3) UTRAN carriers are deployed, the priorapproach in which a mobile station ignores the signaled UTRAN carrierfrequencies after the first three (3) in the list can havedisadvantages. For example, assume that a mobile station is camped on aGERAN (2G) cell and, in the location of this UE, the only carrieroffering UTRAN (3G) coverage is one that is ignored by the mobilestation because it is not among the first three (3) listed frequencies.In such a scenario, the mobile station will be unable to obtain UTRAN(3G) coverage and, thus, will be unable to access the higher data rateservices available in the UTRAN (3G) cell. As another example, even if amobile station is able to obtain service from one of the first three (3)listed UTRAN carrier frequencies, the mobile station may be limited tousing a less optimal UTRAN (3G) cell if a more optimal UTRAN (3G) cellis on a carrier frequency that is not among the first three (3)frequencies and, thus, is ignored by the mobile station. Furthermore, insome scenarios, a mobile station employing the existing inter-frequencymeasurement approach of ignoring carrier frequencies that are not in thefirst three (3) listed frequencies may be unable to reselect to thesubscriber's own femto cell (because its frequency is ignored) and,thus, may be unable to obtain the benefits of using a femto cell (e.g.such as not being able to access the reduced calling rates offered whenby a femto cell).

Table 2 contains an example log collected from a commercial network thatfurther illustrates the limitations of prior inter-frequency measurementapproaches in a mobile network supporting more than three (3) UTRANfrequencies. The example log of Table 2 corresponds to a mobile devicein a dense 3G femto cell environment that has performed cell reselectionto a 2G cell and then is measuring 3G cells from the selected 2G cell.As illustrated in Table 2, the S12-quarter message configures thefollowing five (5) UARFCNs: UARFCN 462, UARFCN 487, UARFCN 4358, UARFCN4383 and UARFCN 4457. The mobile device conforms to the priorinter-frequency measurement approach and, thus, considers only the firstthree UARFCNs from SI2-Quarter. As such, the mobile station performsmeasurements on the first three UARFCNs (462, 487 and 4358), and ignoresthe last two UARFCNs (4383, 4457). Ironically, during operation, themobile station had moved to its 2G cell from a 3G having UARFCN 4457,but it could not return to that same cell because the mobile stationignored that cell's frequency per the prior inter-frequency measurementapproach.

TABLE 2 SYSTEM INFORMATION TYPE 2 QUATER Utran FDD description struct:FDD-ARFCN: 462 FDD_Indic0: 0 NR_OF_FDD_CELLS: 3FDD_CELL_INFORMATION_Field: (28 bits) Scrambling Code: 0x02c Diversity:0 Scrambling Code: 0x177 Diversity: 0 Scrambling Code: 0x179 Diversity:0 FDD-ARFCN: 487 FDD_Indic0: 0 NR_OF_FDD_CELLS: 3FDD_CELL_INFORMATION_Field: (28 bits) Scrambling Code: 0x02c Diversity:0 Scrambling Code: 0x177 Diversity: 0 Scrambling Code: 0x179 Diversity:0 FDD-ARFCN: 4358 FDD_Indic0: 0 NR_OF_FDD_CELLS: 3FDD_CELL_INFORMATION_Field: (28 bits) Scrambling Code: 0x02c Diversity:0 Scrambling Code: 0x177 Diversity: 0 Scrambling Code: 0x179 Diversity:0 FDD-ARFCN: 4383 FDD_Indic0: 0 NR_OF_FDD_CELLS: 3FDD_CELL_INFORMATION_Field: (28 bits) Scrambling Code: 0x02c Diversity:0 Scrambling Code: 0x177 Diversity: 0 Scrambling Code: 0x179 Diversity:0 FDD-ARFCN: 4457 FDD_Indic0: 0 NR_OF_FDD_CELLS: 6FDD_CELL_INFORMATION_Field: (52 bits) Scrambling Code: 0x1f8 Diversity:0 Scrambling Code: 0x1f9 Diversity: 0 Scrambling Code: 0x1fa Diversity:0 Scrambling Code: 0x1fb Diversity: 0 Scrambling Code: 0x1fc Diversity:0 Scrambling Code: 0x1fd Diversity: 0

Table 3 contains another example log collected from another commercialnetwork that illustrates yet another limitation of prior inter-frequencymeasurement approaches in a mobile network supporting more than three(3) UTRAN frequencies. The example log of Table 3 corresponds to amobile device operating in a 2G cell with a neighboring UTRAN TDDnetwork. As illustrated in Table 3, the SI2-quarter message indicatesthat there are nine (9) neighboring 3G frequencies for which the mobilestation is being requested to perform measurements. However, if themobile station implements the existing inter-frequency measurementapproach, the mobile station would measure only the first three (3)listed frequencies and ignore the rest (see Table 1).

TABLE 3 SYSTEM INFORMATION TYPE 2 QUATER  3G Neighbour cell description:  Utran FDD description struct:    FDD-ARFCN: 0     FDD_Indic0: 0    NR_OF_FDD_CELLS: 0     FDD_CELL_INFORMATION_Field: (0 bits)   UtranTDD description struct:    Bandwidth_TDD: 1    TDD-ARFCN: 10055    TDD_Indic0: 0     NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10063    TDD_Indic0: 0     NR_OF_TDD_CELLS: 31  3G Measurement parametersdescription:   Qsearch_I: 8 (−78 dB)   Qsearch_C_Initial: 0 (useQsearch_I)   TDD_Qoffset: 8   TDD_MULTIRAT_REPORTING: 0  GPRS 3GMeasurement Parameters description:   Qsearch_P: 8 (−78 dB)  3G_SEARCH_PRIO: 0 SYSTEM INFORMATION TYPE 2 QUATER  BA_IND: 1 3G_BA_IND: 0  MP_CHANGE_MARK: 0  SI2quater_INDEX: 1  SI2quater_COUNT: 2 3G Neighbour cell description:   Utran FDD description struct:   FDD-ARFCN: 0     FDD_Indic0: 0     NR_OF_FDD_CELLS: 0    FDD_CELL_INFORMATION_Field: (0 bits)   Utran TDD description struct:   Bandwidth_TDD: 1    TDD-ARFCN: 10071     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10080     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10088     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10096     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31 SYSTEM INFORMATION TYPE 2 QUATER  BA_IND: 1 3G_BA_IND: 0  MP_CHANGE_MARK: 0  SI2quater_INDEX: 2  SI2quater_COUNT: 2 3G Neighbour cell description:   Utran FDD description struct:   FDD-ARFCN: 0     FDD_Indic0: 0     NR_OF_FDD_CELLS: 0    FDD_CELL_INFORMATION_Field: (0 bits)   Utran TDD description struct:   Bandwidth_TDD: 1    TDD-ARFCN: 10104     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10112     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31    TDD-ARFCN: 10120     TDD_Indic0: 0    NR_OF_TDD_CELLS: 31

FIG. 2 illustrates an example implementation of the mobile station 125of FIG. 1 that supports inter-frequency measurement processing asdisclosed herein. The mobile station 125 may be implemented by any typeof mobile station or UE equipment or, more generally, any type ofwireless device, such as a smartphone, a mobile telephone device that isportable, a mobile telephone device implementing a stationary telephone,a personal digital assistant (PDA), etc. As discussed above, priormobile stations may implement an existing inter-frequency measurementapproach in which inter-frequency measurement is performed for up to thefirst three (3) UTRAN frequencies in FDD mode and/or the first three (3)UTRAN frequencies in TDD mode that are signaled by the network, with anyadditional signaled UTRAN frequencies being ignored by the mobilestation. Unlike such prior mobile stations, the mobile station 125 ofthe illustrated example implements one or more example inter-frequencymeasurement techniques, and/or combinations thereof, that enableprioritization of frequencies for which measurement is to be performed,with the prioritization being based, at least in part, on informationseparate from the list of frequencies (e.g., the list of neighbor cellinformation) signaled by the network. In other words, when the set offrequencies signaled by the mobile network 100 to the mobile station 125exceeds the monitoring capabilities of the mobile station 125 (e.g.,such as when the number of frequencies for cells operating in a certainmodes exceeds a particular number, such as three (3) for FDD mode andthree (3) or eight (8) for TDD mode), the mobile station can prioritizemeasurement of a subset of these frequencies based, at least in part, oninformation other than just selecting the first two (2) or three (3)frequencies listed in the signaled set of frequencies.

For example, to implement inter-frequency measurement processing asdisclosed herein, the mobile station 125 illustrated in the example ofFIG. 2 includes an example measurement information receiver 205 toreceive information, such as one or more neighbor cell lists, specifyingone or more frequencies of neighbor cells for which the network 100expects measurements to be performed. The measurement informationreceiver 205 can be implemented by any type of receiver capable ofreceiving and decoding broadcast and/or dedicated signaling messagesconveying the list(s) specifying the set of one or more frequencies forwhich measurements for UE controlled and/or network controlled cellselection and/or reselection are to be performed. For example, themeasurement information receiver 205 can correspond to anyimplementation capable of receiving and decoding broadcast UTRAN SystemInformation Block (SIB) messages (e.g., Type 3, 4, 11, 11bis, 12 and/or19 messages), broadcast GERAN SI messages (e.g., SI-2 quarter messages),dedicated UTRAN MOBILITY INFORMATION messages, GERAN MeasurementInformation and/or GERAN Packet Measurement Order messages, etc.

The example mobile station 125 illustrated in FIG. 2 also includes anexample configuration information storage 210 to store theinter-frequency measurement configuration information (e.g., theneighbor cell list(s)) obtained from the network 100. The configurationinformation storage 210 can be implemented by any type and/orcombination of memory and/or storage technology, such as the volatilememory 1518 and/or the mass storage device 1530 of the processing system1500 illustrated in FIG. 15, which is described in greater detail below.The configuration information storage 210 can store the inter-frequencymeasurement configuration information obtained from the network 100 inany appropriate data format.

The example mobile station 125 illustrated in FIG. 2 further includes anexample measurement processor 215 to perform one or more exampletechniques disclosed herein for performing inter-frequency measurements.In the illustrated example, the measurement processor 215 obtains, fromthe configuration information storage 210, a set of frequencies thathave been signaled by the network 100 in one or more lists (e.g.,neighbor cell list(s)) specifying the frequencies for which measurementsare to be performed (e.g., for cell selection and/or re-selection). Theexample technique(s), or combination(s) of techniques, performed by themeasurement processor 215 involve prioritizing measurement of a subsetof the signaled set of frequencies based, at least in part, oninformation separate from of list of specified frequencies obtained fromthe network 100. An example implementation of the measurement processor215 is illustrated in FIG. 3, which is described in greater detailbelow.

FIG. 2 also illustrates an example network element 220 that can be usedto implement at least some of the example inter-frequency measurementprocessing techniques disclosed herein. For example, the network element220 can support receiving measurement limitation information signaled bythe mobile station 125, and processing such signaled measurementlimitation information to revise the neighbor cell list(s) that are sentto mobile stations, such as the mobile station 125, to specify the setof frequencies for which measurements are to be performed. The networkelement 220 can correspond to, for example, an example base stationsubsystem (BSS), a base station transceiver (BTS), a base stationcontroller (BSC), a packet control unit (PCU), a network cell, a Node B,a radio network controller (RNC), etc., or a combination thereof. Anexample implementation of the network element 220 is illustrated in FIG.5, which is described in greater detail below.

An example implementation of the measurement processor 215 of FIG. 2 isillustrated in FIG. 3. The example measurement processor 215 of FIG. 2includes an example measurement scheduler 305, an example carrierfrequency prioritizer 310, an example neighbor prioritizer 315 inconjunction with an example neighbor database 320, an example RSSImeasurement processor 325, an example reselection-based prioritizer 330,an example measurement limitation signaler 335, an example carrierfrequency selector 340 and an example macro cell prioritizer 345, eachof which implement a different example technique for performinginter-frequency measurement processing as disclosed herein. Although theexample measurement processor 215 of FIG. 2 is shown to include all ofthe measurement scheduler 305, the carrier frequency prioritizer 310,the neighbor prioritizer 315, the neighbor database 320, the RSSImeasurement processor 325, the reselection-based prioritizer 330, themeasurement limitation signaler 335, the carrier frequency selector 340and the macro cell prioritizer 345, in other examples the measurementprocessor 215 could include just one or some of these elements (e.g., toimplement one or different combinations of the example disclosedtechniques).

Turning to FIG. 3, for scenarios in which the mobile network 100includes GERAN (2G) network cell(s) 105A-C that signal neighbor celllist(s) containing more than three (3) UTRAN frequencies, or UTRAN (3G)cell(s) 110A-C and/or 115A-C that signal neighbor cell list(s)containing more than two (2) UTRAN inter-frequencies, the measurementscheduler 305 can schedule measurements to enable the mobile station 125to perform measurements on all of the UTRAN carrier frequencies that areconfigured in the neighbor cell list information, rather than limitingmeasurement to just 2 or 3 frequencies as in the prior approaches. Thereare at least two variants of measurement scheduling that can beimplemented by the measurement scheduler 305. In a first variant, themeasurement scheduler 305 causes the mobile station 125 to performmeasurements on all of the frequencies specified in the signaledneighbor cell lists with the same performance (e.g., in terms of therate at which measurements are performed and the corresponding delay indetecting and reselecting to a neighbor cell) as specified by theexisting 3GPP specifications for a maximum of 2 UTRAN inter-frequencies(from a UTRAN/3G cell) and 3 UTRAN frequencies (from a GERAN/2G cell).To achieve this performance, the first measurement scheduling variant asimplemented by the measurement scheduler 305 may necessitate increasesin complexity and/or power consumption of the mobile station 125 to beable to support more inter-frequency measurements with the sameperformance as existing mobile stations.

In a second variant, the measurement scheduler 305 causes the mobilestation 125 to perform measurements on all of the specified frequencies,but with a performance that is relaxed compared to the performancespecified by the existing 3GPP specifications for a maximum of 2 UTRANinter-frequencies (for measurements from a UTRAN/3G cell) and 3 UTRANfrequencies (for measurements from a GERAN/2G cell). In other words,under the second variant, the measurement scheduler 305 schedulesinter-frequency measurements at, for example, a reduced rate scaledproportionally to the number of frequencies on which the mobile station125 is to perform measurements. Thus, the second measurement schedulingvariant can be used to increase the number of UTRAN frequencies forwhich measurements are performed while maintaining similar complexityand power consumption as in prior mobile stations. However, the secondmeasurement scheduling variant may exhibit reduced measurementperformance and, for example, longer reselection delays.

Measurement scheduling as performed by the measurement scheduler 305 canbe combined with one or more of the frequency prioritization techniquesdescribed in greater detail below. For example, measurement schedulingas performed by the measurement scheduler 305 could be used to increasethe number of frequencies that the mobile station 125 is required tomeasure (e.g., by 1 or 2 frequencies) and then one or more of theprioritization techniques described below could be used if the number offrequencies indicated by the network 100 still exceeds the new limit.

The carrier frequency prioritizer 310 can be included in the measurementprocessor 215 to prioritize measurements for one or more UTRAN carrierfrequencies that the mobile station 125 last visited (or, in otherwords, most recently visited). In general, the last visited UTRANcarrier frequency refers to the UTRAN carrier frequency of the UTRANcell most recently used by the mobile station 125 or, in other words, towhich the mobile station 125 was most recently associated. The UTRANcell to which the mobile station 125 was most recently associated may bethe cell on which the mobile station 125 was camped in idle mode, or onwhich the mobile station 125 was camped in the URA_PCH, CELL_FACH orCELL_FACH states of connected mode. Additionally, a UTRAN cell to whichthe mobile station 125 was most recently associated may be a cell withwhich the mobile station 125 was connected in the CELL_DCH state ofconnected mode.

For example, the carrier frequency prioritizer 310 could prioritize thelast visited UTRAN carrier frequency, in which case the carrierfrequency prioritizer 310 causes the mobile station 125 to measure cellson this UTRAN carrier frequency regardless of the frequency's locationin the neighbor cell list (assuming this last visited frequency is atleast somewhere in the list). The carrier frequency prioritizer 310could then permit measurement on other UTRAN carrier frequencies in theneighbor cell list (for example, based on the order in which the UTRANcarrier frequencies appear in the list, and/or based on otherprioritization techniques, such as those described below).Prioritization of the last visited UTRAN frequency can address theproblem experienced in prior systems in which a prior mobile station maynot be able to return to its last visited UTRAN cell because thefrequency of that cell is ignored by the mobile station.

The carrier frequency prioritizer 310 can implement one or more variantsand/or additions to the principle of prioritizing the last visited UTRANcarrier frequency. Furthermore, these variants/additions can be combinedin any manner. For example, the carrier frequency prioritizer 310 couldprioritize more than just the last visited UTRAN carrier frequency, andcould instead store and prioritize more than one (e.g., 2 or 3 or more)of the most recent visited UTRAN carrier frequencies (e.g., with theprioritizing being in reverse chronological order beginning with themost recently visited UTRAN frequency).

As described above, the carrier frequency prioritizer 310 may considerthat the UTRAN cell to which the mobile station 125 was most recentlyassociated corresponds to the cell on which the mobile station 125 wasmost recently camped. In some examples, the carrier frequencyprioritizer 310 could further qualify the most recently associated UTRANcell(s) to correspond to only cell(s) on which the mobile station 125was camped to obtain normal service. This would avoid the carrierfrequency prioritizer 310 from prioritizing the frequencies of UTRANcells with which the mobile station 125 was camped, but was unable toobtain normal service. For example, the mobile station 125 may camp on acell for emergency services when no other cell offering normal serviceis available. Normal service could be defined in a number of ways. Forexample, normal service could follow the definition of sub-clause 3.2.1of 3GPP TS 43.022, Functions Related to Mobile Station (MS) in Idle Modeand Group Receive Mode, v10.0.0, March 2011, and, thus, mean theopposite of a limited service state. As another example, normal servicecould mean that the mobile station 125 was able to access both packetswitched (PS) and circuit switched (CS) services in the cell (in otherwords, the mobile station 125 was successfully attached in both CS andPS domains). Additionally or alternatively, the carrier frequencyprioritizer 310 could use one or more other requirement in terms of theservice(s) available to the mobile station 125 to determine whether thenormal service is available in a particular cell. In some examples, whenthe mobile station 125 is already in a limited service state, thecarrier frequency prioritizer 310 ignores the restriction that the mostrecently associated UTRAN cell(s) only correspond to cell(s) on whichthe mobile station 125 was camped to obtain normal service.

In some examples, the carrier frequency prioritizer 310 clears itsstored list of the one or more most recently visited UTRAN frequenciesunder some situations. For example, the carrier frequency prioritizer310 could clear its list of most recently visited UTRAN frequencies whenthe mobile station 125 is powered off or on, (e.g., because the mobilestation 125 may be powered on in a completely different location suchthat the stored information may not correspond to the network deploymentin the new location.) Additionally or alternatively, the carrierfrequency prioritizer 310 could clear its list of most recently visitedUTRAN frequencies when a new (PLMN) is selected (e.g., because thestored information may not correspond to the network deployment of thenew PLMN). Additionally or alternatively, the carrier frequencyprioritizer 310 could remove an entry for a particular UTRAN carrierfrequency from its list of most recently visited UTRAN frequencies if noUTRAN cell has been detected on that carrier frequency for some periodof time. This could occur if, for example, the mobile station 125 hasmoved to a location where that UTRAN carrier frequency is not deployedand, as such, it no longer makes sense for the mobile station 125 toprioritize that carrier frequency. A variant of the condition forclearing an entry in the list could be that the mobile station 125 hasnot camped on a cell on that carrier frequency for some period of time.

In some examples, for UTRAN carrier frequencies included in the neighborcell list signaled by the network 100 but that are not prioritized bythe carrier frequency prioritizer 310 (e.g., because they are not amongthe one or more last visited carrier frequencies), the carrier frequencyprioritizer 310 can cause the mobile station 125 to perform around-robin measurement process to search for cells on these remainingfrequencies. If, for example, the mobile station 125 detects a cell onone of these remaining UTRAN carrier frequencies, then the carrierfrequency prioritizer 310 can cause the mobile station 125 to continueto perform measurements in that frequency. However, if the mobilestation 125 does not detect any cells on a remaining UTRAN carrierfrequency, then the carrier frequency prioritizer 310 can cause themobile station 125 to move on to search on another remaining UTRANcarrier frequency.

In some examples, the carrier frequency prioritizer 310 cande-prioritize one or more UTRAN carrier frequencies included in theneighbor cell list signaled by the network 100. For example, the carrierfrequency prioritizer 310 can de-prioritize a UTRAN frequency if themobile station 125 previously was unsuccessful in an attempt to camp andregister on a cell of that frequency. Examples of cases where the mobilestation 125 may be unsuccessful in an attempt to camp and register on acell include, but are not limited to, when the mobile station 125attempts to camp on a cell and determines that the cell belongs to aforbidden PLMN or forbidden location area (LA) for roaming, or when themobile station 125 attempts to register (e.g. to perform a location orrouting area update) on a cell and is rejected by that cell. As anexample of the latter, if the cell is a CSG cell, the mobile station 125may be rejected because it does not have a valid CSG subscription.

In some examples, as a general rule, the carrier frequency prioritizer310 can additionally or alternatively de-prioritize frequencies on whichCSG cells are known to operate because there is a reasonable likelihoodthat (i) the coverage of such cells will be limited, and (ii) the mobilestation 125 may not be permitted access to such cells. In some examples,such UTRAN frequencies may be differentiated (and prioritizedaccordingly) depending on whether CSG cells and macro cells are known toco-exist on the same frequency or whether the frequency is aCSG-specific frequency. For example, mixed frequencies can be rankedhigher than CSG-only frequencies. In some examples, UTRAN frequencies onwhich CSG cells are known to operate may be differentiated (andprioritized accordingly) depending on whether access to CSG cells onthat frequency has recently been permitted or rejected. For example,frequencies on which access to CSG cells has succeeded may be rankedhigher than frequencies on which CSG access has failed.

In some examples, the carrier frequency prioritizer 310 maintains a listof UTRAN frequencies that it has been requested by the network tomeasure (e.g., which may correspond to a set of frequencies signaled viaone or more neighbor cell lists). In such an example, the carrierfrequency prioritizer 310 may associate each UTRAN frequency in itsmaintained list with a binary classification, such as marking of‘measure’ or ‘do not measure’ to indicate which frequencies have beenprioritized for measurement. Additionally or alternatively, the carrierfrequency prioritizer 310 may associate each UTRAN frequency in itsmaintained list with a ranking such that frequencies with higher rankingare the frequencies that would be measured (e.g., within the monitoringcapabilities of the mobile station 125). For example, the ranking scoremay be a rank value (e.g., from 1 to N where there are N frequenciesunder consideration) or may be a score based on one or more of theprioritization criteria described above.

The neighbor prioritizer 315 can be included in the measurementprocessor 215 to prioritize measurement of UTRAN frequencies that arelikely to actually contain neighbor cells from which the mobile station125 can obtain service. For example, the neighbor prioritizer 315 canprioritize those UTRAN carrier frequencies that include UTRAN (3G) cellswith which the mobile station 125 was previously associated and that hadsignaled neighbor cell lists indicating that the current serving cell ofmobile station 125 was a neighbor cell. In the illustrated example, asthe mobile station 125 is performing cell selection and reselectionswithin the network 100, the neighbor prioritizer 315 can gather dataabout the relationship(s) between a particular UTRAN carrier frequencyand any 2G/3G neighbor cell(s) and store the neighbor relationship(s) inthe neighbor database 320. The neighbor database 320 can be implementedby any type and/or combination of memory and/or storage technology, suchas the volatile memory 1518 and/or the mass storage device 1530 of theprocessing system 1500 illustrated in FIG. 15, which is described ingreater detail below. The neighbor database 320 can store the neighborinformation gathered from the network 100 in any appropriate dataformat.

For example, when the mobile station 125 is camping in the mobilenetwork 100 on the 3G cell 110B having UTRAN carrier frequency F1, theneighbor prioritizer 315 can record the 2G/3G cells that are listed inthe system information signaled by the 3G cell 110B. By listing these2G/3G cells as neighbor cells of the 3G cell 110B, the network operatoris indicating that it expects reselection from the 3G cell 110B to thoseneighbor 2G/3G cells to be possible. It is reasonable to assume,therefore, that the network operator expects reselection in the oppositedirection to also be possible. As such, when the mobile station 125 islater camped on one of those 2G/3G cells, the neighbor prioritizer 315can intelligently prioritize measurement of the UTRAN carrier frequencyF1 corresponding to the 3G cell 110B, thus ensuring that reselectionback to the 3G cell 110B is possible. Such prioritization by theneighbor prioritizer 315 can address the problem exhibited by priormobile network in which a prior mobile station could not return to theUTRAN cell on which it was previously camped (because it had ignored thefrequency of that UTRAN cell).

An example operation of the neighbor prioritizer 315 in an examplemulti-RAT mobile network 400 is illustrated in FIG. 4. The mobilenetwork 400 includes a large GERAN (2G) cell 405, which may correspondto a 2G cell deployed in a rural area. The mobile network 400 alsoincludes UTRAN cells 410A-E on different UTRAN frequencies, which maycorrespond to a multi-frequency deployment in an urban environment.Assume that the mobile station follows an example path 415 asillustrated in FIG. 4. In such an example, when the mobile station 125is in the 2G cell 405, the neighbor prioritizer 315 will prioritize the3G cells/UARFCNs it has previously seen and which have considered the 2Gcell 405 to be a neighbor cell. In the illustrated example of FIG. 4,these UTRAN frequencies prioritized by the neighbor prioritizer 315 arethe UARFCNs 4457 and 4353 corresponding to the 3G cells 410A and 410B.

Returning to FIG. 3, the RSSI measurement processor 325 can be includedin the measurement processor 215 to perform RSSI measurements on theeach frequency in the set of UTRAN carrier frequencies for whichmeasurements have been requested by the network 100 (e.g., via inclusionin the signaled neighbor cell list(s)). The RSSI measurement processor325 can then prioritize measurement of UTRAN frequencies based on theRSSI measurements (e.g., in order of decreasing RSSI). RSSI measurementsare relatively quick to perform (e.g., usually faster than attempting todetect a cell) and can indicate whether there is energy within thechannel. In general, the likelihood of detecting a cell on a carrierfrequency increases with increasing RSSI. After performing an RSSImeasurement on all of the UTRAN carrier frequencies specified by thenetwork 100, the RSSI measurement processor 325 can prioritize furthermeasurement activity on those frequencies with the highest RSSI. TheRSSI measurement on all of the specified UTRAN carriers may be repeatedat regular intervals to support mobile station mobility and, inparticular, scenarios in which the mobile station 125 moves to alocation where coverage is available from different carrier frequencies.

The reselection-based prioritizer 330 can be included in the measurementprocessor 215 to prioritize measurement of UTRAN frequencies based onreselection priorities. In some examples, the mobile network 100 canimplement a priority based cell reselection algorithm. If a prioritybased cell reselection algorithm is deployed in the mobile network 100,then each carrier frequency (from different RATs) is assigned areselection priority, and the mobile station 125 attempts to camp on thefrequency with the highest reselection highest priority. If the mobilestation 125 is requested by the network 100 to measure a number of UTRAN(3G) carrier frequencies that exceeds its monitoring capabilities, thenthe reselection-based prioritizer 330 can cause the mobile station 125to measure a subset of the UTRAN (3G) carrier frequencies that have thehighest reselection priority or priorities (e.g., prioritized indescending order of reselection priority). If different UTRAN carrierfrequencies are assigned the same cell reselection priority, then themeasurement processor 215 can apply another of the inter-frequencymeasurement prioritization techniques disclosed herein to determinewhich frequencies to measure.

The measurement limitation signaler 335 can be included in themeasurement processor 215 to detect that the set of frequencies forwhich the network 100 has indicated measurements are to be performedexceeds the monitoring capabilities of the mobile station 125. Themeasurement limitation signaler 335 can then indicate to the network 100that its monitoring capabilities have been exceeded. In some examples,the measurement limitation signaler 335 can also send a prioritized listof UTRAN frequencies to the network 100, with the prioritized list ofUTRAN frequencies being determined using one or more of theinter-frequency measurement prioritization techniques disclosed herein.Additionally or alternatively, the measurement limitation signaler 335could send location information to the network 100 indicating a locationof the mobile station 125 and, thus, a location to be associated with aparticular prioritized list of UTRAN frequencies.

In such an example, after receiving the measurement limitationinformation signaled by the measurement limitation signaler 335, themobile network 100 is responsible for updating the order of thefrequencies in the neighbor cell list(s) of the system informationmessages and/or dedicated messages sent in the relevant cells. Anexample implementation of the network element 220 of FIG. 2 that iscapable of processing the measurement limitation information signaled bythe measurement limitation signaler 335 is illustrated in FIG. 5. Theexample network element 220 of FIG. 5 includes an example measurementlimitation receiver 505 to receive measurement limitation informationfrom a mobile station, such as the mobile station 125. The measurementlimitation receiver 505 can correspond to any type of receiver capableof receiving and decoding information conveyed in one or more mobilestation signaling messages.

The example network element 220 of FIG. 5 also includes an examplemeasurement information database 510 to store the measurement limitationinformation obtained from mobile stations, such as the mobile station125, in the mobile network 100. The measurement limitation informationstored in the measurement information database 510 can include, forexample, prioritized lists of UTRAN frequencies signaled by the mobilestations, location information provided by the mobile stations to beassociated with the prioritized lists of UTRAN frequencies, etc. Themeasurement information database 510 can be implemented by any typeand/or combination of memory and/or storage technology, such as thevolatile memory 1518 and/or the mass storage device 1530 of theprocessing system 1500 illustrated in FIG. 15, which is described ingreater detail below. The measurement information database 510 can storethe measurement limitation information received from one or more mobilestations in any appropriate data format.

The example network element 220 of FIG. 5 also includes an exampleneighbor information signaler 515 to update the set(s) of frequencies,as well as the order of the frequencies, in the neighbor cell list(s) tobe sent to mobile stations, such as the mobile station 125, operating inthe mobile network 100. The neighbor information signaler 515 updatesthe set and order of frequencies included in a neighbor cell list basedon the prioritization and/or location information stored in themeasurement information database 510. The neighbor information signaler515 also causes the network element 220 to transmit the updated neighborcell list(s) in the appropriate system information messages and/ordedicated messages.

In some examples, measurement limitation signaling as performed by themeasurement limitation signaler 335 could be implemented in a3GPP-compliant network by adding this feature as another use case in the3GPP specifications directed to Self-Organizing Network (SON)functionality, and/or by adding this feature as an extension to theAutomated Neighbor Relation (ANR) feature, and/or by including thisfeature as part of the Minimization of Drive Testing (MDT) feature.

A possible advantage of measurement limitation signaling as performed bythe measurement limitation signaler 335 is that, after the order offrequencies in the neighbor cell list(s) is updated in the network 100,even legacy mobile stations with limited inter-frequency measurementscapabilities could benefit from the updated order of the frequencies forwhich the network requests measurements. Also, measurement limitationsignaling can be implemented without modifying existing measurementsperformance requirements.

Returning to FIG. 3, the carrier frequency selector 340 can be includedin the measurement processor 215 to prioritize measurement of UTRANfrequencies based on the order in which they appear in the neighbor celllist(s) signaled by the mobile network 100. For example, the carrierfrequency selector 340 can be configured to cause the mobile station 125to always measure the first listed UTRAN carrier frequency provided in alist signaled by the mobile network 100. This functionality can give anetwork operator some degree of control to ensure that the mobilestation 125 is guaranteed to measure at least this one particularcarrier frequency included in the list. As such, the operator couldchoose to place a UTRAN carrier frequency known to provide the bestcoverage in a particular geographic location as the first frequency inthe signaled neighbor cell list.

In some examples, for other UTRAN carrier frequencies listed in thesignaled neighbor cell list, the mobile station 125 could applyprioritization in accordance with one or more of the otherprioritization techniques disclosed herein to determine a subset ofadditional frequencies for which measurements are to be performed. Suchprioritization can be based on information separate from the signaledneighbor cell lists, such as prioritization based on a list offrequencies with which the mobile station 125 has be recentlyassociated, prioritization based on gathered neighbor cell information,prioritization based on RSSI measurements, prioritization based on cellreselection priorities, etc., or combination(s) thereof.

In some examples, the carrier frequency selector 340 can extendfrequency selection to cause the mobile station 125 to measure on thefirst N UTRAN carrier frequencies listed in the signaled neighbor celllist. If the monitoring capabilities of the mobile station 125 are notexceeded by measuring these first N frequencies, the mobile station 125could apply prioritization in accordance with one or more of theprioritization techniques disclosed herein, and based on the informationdescribed above, to determine a subset of carrier frequencies beyond thefirst N frequencies for which measurements are to be performed (e.g., upto the limit of the mobile station's monitoring capabilities).

The macro cell prioritizer 345 can be included in the measurementprocessor 215 to prioritize measurement of UTRAN frequencies based onfrequencies in which UTRAN (3G) macro cell(s) are most likely deployed.Many operators deploy their networks such that one or a few carrierfrequencies (also referred to as carriers) provide maximum coverage.These carriers can support macro cells with large coverage areasachieved by high power basestations, high mounted antennas, etc. Such acarrier frequency can offer a relatively strong likelihood ofidentifying a candidate cell for reselection. Thus, the macro cellprioritizer 345 attempts to prioritize such a carrier (or carriers) inthe set of UTRAN carrier frequencies that are to be monitored by themobile station 125.

However, in at least some examples, the broadcast system informationdoes not provide an explicit indication of the macro coverage layer. Insuch examples, the macro cell prioritizer 345 determines the UTRANcarrier frequency or frequencies most likely to be associated with amacro coverage layer from other information that is available. Forexample, broadcast system information can provide a cell transmit powerlevel, which the macro cell prioritizer 345 can use to infer thecoverage level of the cell. For instance, in a commercial network, the“primaryCPICH-TX-Power” information element in System Information Block5 set can be set to a number, such as the number “34,” representative ofthe transmission power of the primary common pilot channel (whichdetermines the cell coverage), which in this example means that theprimary common pilot channel has a transmission power of 34 dBm. As afurther example, the macro cell prioritizer 345 can assume that theUTRAN carrier or carriers having the lowest carrier frequency orfrequencies are associated with the macro coverage layer(s). Lowfrequencies generally have better propagation properties, therebyproviding better cell coverage. Thus, operators may choose one or morecarriers from a low frequency band for deploying macro cells.Additionally or alternatively, the macro cell prioritizer 345 can assumethat the UTRAN carrier or carriers associated with the most neighborcells in the signaled neighbor cell list(s) are associated with themacro coverage layer(s). A carrier frequency associated with a largenumber of neighbor cells in a neighbor cell list suggests that thiscarrier frequency has been planned to provide a high degree of coverage.

While example manners of implementing the mobile station 125 and thenetwork element 220 have been illustrated in FIGS. 2-5, one or more ofthe elements, processes and/or devices illustrated in FIG. 2-5 may becombined, divided, re-arranged, omitted, eliminated and/or implementedin any other way. Further, the example measurement information receiver205, the example configuration information storage 210, the examplemeasurement processor 215, the example measurement scheduler 305, theexample carrier frequency prioritizer 310, the example neighborprioritizer 315, the example neighbor database 320, the example RSSImeasurement processor 325, the example reselection-based prioritizer330, the example measurement limitation signaler 335, the examplecarrier frequency selector 340, the example macro cell prioritizer 345,the example measurement limitation receiver 505, the example measurementinformation database 510, the example neighbor information signaler 515and/or, more generally, the example mobile station 125 and/or theexample network element 220 may be implemented by hardware, software,firmware and/or any combination of hardware, software and/or firmware.Thus, for example, any of the example measurement information receiver205, the example configuration information storage 210, the examplemeasurement processor 215, the example measurement scheduler 305, theexample carrier frequency prioritizer 310, the example neighborprioritizer 315, the example neighbor database 320, the example RSSImeasurement processor 325, the example reselection-based prioritizer330, the example measurement limitation signaler 335, the examplecarrier frequency selector 340, the example macro cell prioritizer 345,the example measurement limitation receiver 505, the example measurementinformation database 510, the example neighbor information signaler 515and/or, more generally, the example mobile station 125 and/or theexample network element 220 could be implemented by one or morecircuit(s), programmable processor(s), application specific integratedcircuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)), etc. In at least some exampleimplementations, at least one of the example mobile station 125, theexample network element 220, the example measurement informationreceiver 205, the example configuration information storage 210, theexample measurement processor 215, the example measurement scheduler305, the example carrier frequency prioritizer 310, the example neighborprioritizer 315, the example neighbor database 320, the example RSSImeasurement processor 325, the example reselection-based prioritizer330, the example measurement limitation signaler 335, the examplecarrier frequency selector 340, the example macro cell prioritizer 345,the example measurement limitation receiver 505, the example measurementinformation database 510 and/or the example neighbor informationsignaler 515 are hereby expressly defined to include a tangible computerreadable medium such as a memory, digital versatile disk (DVD), compactdisk (CD), etc., storing such software and/or firmware. Further still,the example mobile station 125 and/or the example network element 220may include one or more elements, processes and/or devices in additionto, or instead of, those illustrated in FIGS. 2-5, and/or may includemore than one of any or all of the illustrated elements, processes anddevices.

Flowcharts representative of example processes that may be executed toimplement the example mobile station 125, the example network element220, the example measurement information receiver 205, the exampleconfiguration information storage 210, the example measurement processor215, the example measurement scheduler 305, the example carrierfrequency prioritizer 310, the example neighbor prioritizer 315, theexample neighbor database 320, the example RSSI measurement processor325, the example reselection-based prioritizer 330, the examplemeasurement limitation signaler 335, the example carrier frequencyselector 340, the example macro cell prioritizer 345, the examplemeasurement limitation receiver 505, the example measurement informationdatabase 510 and/or the example neighbor information signaler 515 areshown in FIGS. 6-14. In these examples, the process represented by eachflowchart may be implemented by one or more programs comprising machinereadable instructions for execution by a processor, such as theprocessor 1512 shown in the example processing system 1500 discussedbelow in connection with FIG. 15. Alternatively, the entire program orprograms and/or portions thereof implementing one or more of theprocesses represented by the flowcharts of FIGS. 6-14 could be executedby a device other than the processor 1512 (e.g., such as a controllerand/or any other suitable device) and/or embodied in firmware ordedicated hardware (e.g., implemented by an ASIC, a PLD, an FPLD,discrete logic, etc.). Also, one or more of the processes represented bythe flowchart of FIGS. 6-14, or one or more portion(s) thereof, may beimplemented manually. Further, although the example processes aredescribed with reference to the flowcharts illustrated in FIGS. 6-14,many other techniques for implementing the example methods and apparatusdescribed herein may alternatively be used. For example, with referenceto the flowcharts illustrated in FIGS. 6-14, the order of execution ofthe blocks may be changed, and/or some of the blocks described may bechanged, eliminated, combined and/or subdivided into multiple blocks.

As mentioned above, the example processes of FIGS. 6-14 may beimplemented using coded instructions (e.g., computer readableinstructions) stored on a tangible computer readable medium such as ahard disk drive, a flash memory, a read-only memory (ROM), a CD, a DVD,a cache, a random-access memory (RAM) and/or any other storage media inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, brief instances, for temporarily buffering, and/orfor caching of the information). As used herein, the term tangiblecomputer readable medium is expressly defined to include any type ofcomputer readable storage and to exclude propagating signals.Additionally or alternatively, the example processes of FIGS. 6-14 maybe implemented using coded instructions (e.g., computer readableinstructions) stored on a non-transitory computer readable medium, suchas a flash memory, a ROM, a CD, a DVD, a cache, a random-access memory(RAM) and/or any other storage media in which information is stored forany duration (e.g., for extended time periods, permanently, briefinstances, for temporarily buffering, and/or for caching of theinformation). As used herein, the term non-transitory computer readablemedium is expressly defined to include any type of computer readablemedium and to exclude propagating signals. Also, as used herein, theterms “computer readable” and “machine readable” are consideredequivalent unless indicated otherwise.

An example process 600 that may be executed to implement the examplemobile station 125 described above is illustrated in FIG. 6. Withreference to the preceding figures and associated descriptions, theprocess 600 of FIG. 6 begins execution at block 605 at which themeasurement information receiver 205 of the mobile station 125 receivesinter-frequency measurement configuration information from the mobilenetwork 100. For example, at block 605 the measurement informationreceiver 205 can receive one or more neighbor cell lists specifying aset of one or more UTRAN (3G) carrier frequencies for which the network100 expects measurements to be performed. At block 610, the measurementprocessor 215 of the mobile station 125 determines whether the set offrequencies specified in the inter-frequency measurement configurationinformation exceeds the monitoring capabilities of the mobile station125. If the mobile station's monitoring capabilities are not exceeded,then at block 615 the measurement processor 215 causes the mobilestation 125 to measure the entire set of specified frequencies. However,if the mobile station's monitoring capabilities are exceeded, then atblock 620 the measurement processor 215 performs inter-frequencymeasurement prioritization using one or a combination of the exampletechniques disclosed herein. Example processes that may implement atleast a portion of the processing at block 620 are illustrated in FIGS.7-14, which are described in greater detail below.

An example process 700 that may be used to perform measurementscheduling at block 620 of FIG. 6 and/or to implement the examplemeasurement scheduler 305 in the example mobile station 125 of FIG. 3 isillustrated in FIG. 7. With reference to the preceding figures andassociated descriptions, the process 700 of FIG. 7 begins execution atblock 705 at which the measurement scheduler 305 begins performinginter-frequency measurement scheduling for each RAT supported by themobile station 125. For a particular RAT, at block 708 the measurementscheduler 305 obtains the list(s) (e.g., neighbor cell list(s)) signaledby the network 100 that specify the set of carrier frequenciesconfigured by the network 100 for measurement. At block 710, themeasurement scheduler 305 determines a ratio of the total number offrequencies specified in the set of frequencies contained in themeasurement configuration information (e.g., neighbor cell list(s))obtained from the network 100 to at least one of (1) the number offrequencies for which the mobile station 125 is mandated by the 3GPPspecifications to support measurements, or (2) the number of frequenciesactually supported by the monitoring capabilities of the mobile station125.

At block 715, the measurement scheduler 305 schedules measurement to beperformed by the mobile station 125 for all frequencies included in setof specified frequencies to be measured, but with measurementperformance being scaled down in proportion to the ratio determined atblock 710. For example, the measurement scheduler 305 can scale downmeasurement performance by reducing the measurement repetition rate(e.g., corresponding to how often each frequency is revisited) and/ormeasurement dwell (e.g., corresponding to how much measurement time isspent at each frequency). At block 720, the measurement scheduler 305repeats measurement scheduling for each RAT supported by the mobilestation 125.

An example process 800 that may be used to perform carrier frequencyprioritization at block 620 of FIG. 6 and/or to implement the examplecarrier frequency prioritizer 310 in the example mobile station 125 ofFIG. 3 is illustrated in FIG. 8. With reference to the preceding figuresand associated descriptions, the process 800 of FIG. 8 begins executionat block 805 at which the carrier frequency prioritizer 310 beginsperforming carrier frequency prioritization for each RAT supported bythe mobile station 125. For a particular RAT, at block 808 the carrierfrequency prioritizer 310 obtains the list(s) (e.g., neighbor celllist(s)) signaled by the network 100 that specify the set of carrierfrequencies configured by the network 100 for measurement. At block 810,the carrier frequency prioritizer 310 retrieves its list of the mostrecent N visited frequencies (N≧1). For example, the list retrieved bythe carrier frequency prioritizer 310 at block 810 may be maintained andupdated by a separate process, such as a background process, that keepstrack of the frequencies most recently visited by the mobile station125, as described above. For example, such a process could beimplemented by the carrier frequency prioritizer 310 to: (1) clear thelist or one or more particular frequencies in the list; (2) markfrequencies in the list to indicate whether or not the frequency is tobe measured; (3) rank the frequencies in the list; etc., as describedabove.

At block 820, the carrier frequency prioritizer 310 prioritizes a subsetof frequencies for which measurements are to be performed. For example,and as described above, the carrier frequency prioritizer 310 canprioritize the subset of frequencies to be those frequencies that are inboth the list of most recently visited frequencies and the list offrequencies configured by the network 100 for measurement. At block 820,the carrier frequency prioritizer 310 also limits the size of theprioritized subset of frequencies to be within the monitoringcapabilities of the mobile station 125.

At block 825, the carrier frequency prioritizer 310 determines whetherthe mobile station's monitoring capability has been exhausted. If themonitoring capability has not been exhausted, then at block 830 thecarrier frequency prioritizer 310 can determine any remaining one ormore frequencies in the set of frequencies specified the network 100that can be de-prioritized, as described above, before determining whichof the remaining frequencies are to be measured. At block 835, thecarrier frequency prioritizer 310 performs round-robin measurement (orany other type of measurement scheduling) of the remaining frequenciesin the set of frequencies specified the network 100 for measurement. Atblock 835, the carrier frequency prioritizer 310 can prioritizemeasurement of at least a subset of the remaining frequencies based on,for example, a respective number of cells associated with each remainingfrequency, a respective RSSI determined for each remaining frequency,and/or any other prioritization technique described above. At block 840,the carrier frequency prioritizer 310 repeats carrier frequencyprioritization for each RAT supported by the mobile station 125.

An example process 900 that may be used to perform neighborprioritization at block 620 of FIG. 6 and/or to implement the exampleneighbor prioritizer 315 in the example mobile station 125 of FIG. 3 isillustrated in FIG. 9. With reference to the preceding figures andassociated descriptions, the process 900 of FIG. 9 begins execution atblock 905 at which the neighbor prioritizer 315 begins performingneighbor prioritization processing for each RAT supported by the mobilestation 125. For a particular RAT, at block 908 the neighbor prioritizer315 obtains the list(s) (e.g., neighbor cell list(s)) signaled by thenetwork 100 that specify the set of carrier frequencies configured bythe network 100 for measurement. At block 910, the neighbor prioritizer315 updates the neighbor database 320 using neighbor cell informationgathered from neighbor cell list(s) signaled by the network 100 to themobile station 125. At block 915, the neighbor prioritizer 315 processesthe neighbor cell information stored in the neighbor database 320 todetermine a set of candidate cells for which the network 100 hadpreviously signaled neighbor cell lists including the current servingcell of the mobile station 125.

At block 920, the neighbor prioritizer 315 prioritizes measurement of asubset of frequencies for which measurements are to be performed. Forexample, and as described above, the neighbor prioritizer 315 canprioritize the subset of frequencies to be those frequencies that areassociated with the set of candidate cells determined at block 920 andin the list of frequencies configured by the network 100 formeasurement. At block 920, the neighbor prioritizer 315 also limits thesize of the prioritized subset of frequencies to be within themonitoring capabilities of the mobile station 125. At block 925, thecarrier neighbor prioritizer 315 repeats neighbor prioritization foreach RAT supported by the mobile station 125.

An example process 1000 that may be used to perform RSSI measurementprocessing at block 620 of FIG. 6 and/or to implement the example RSSImeasurement processor 325 in the example mobile station 125 of FIG. 3 isillustrated in FIG. 10. With reference to the preceding figures andassociated descriptions, the process 1000 of FIG. 10 begins execution atblock 1005 at which the RSSI measurement processor 325 begins performingRSSI measurement prioritization processing for each RAT supported by themobile station 125. For a particular RAT, at block 1010 obtains thelist(s) (e.g., neighbor cell list(s)) signaled by the network 100 thatspecify the set of carrier frequencies configured by the network 100 formeasurement. At block 1015, the RSSI measurement processor 325 causesthe mobile station 125 to measure the RSSI for each frequency in the setof carrier frequencies specified by the network 100. At block 1020, theRSSI measurement processor 325 uses the measured RSSI for each frequencyto prioritize a subset of frequencies for which measurements are to beperformed. For example, the RSSI measurement processor 325 canprioritize the subset of frequencies to be those frequencies having thehighest RSSI measurements. At block 1020, the RSSI measurement processor325 also limits the size of the prioritized subset of frequencies to bewithin the monitoring capabilities of the mobile station 125. At block1025, the carrier RSSI measurement processor 325 repeats RSSImeasurement prioritization processing for each RAT supported by themobile station 125. In some examples, the process 1000 may be repeatedat regular intervals, for example, every 2 minutes, 5 minutes, 10minutes, etc., to support mobile station mobility, such as scenarios inwhich the mobile station 125 moves to a location where coverage isavailable from different carrier frequencies.

An example process 1100 that may be used to perform reselectionprioritization at block 620 of FIG. 6 and/or to implement the examplereselection-based prioritizer 330 in the example mobile station 125 ofFIG. 3 is illustrated in FIG. 11. With reference to the precedingfigures and associated descriptions, the process 1100 of FIG. 11 beginsexecution at block 1105 at which the reselection-based prioritizer 330begins performing reselection prioritization processing for each RATsupported by the mobile station 125. For a particular RAT, at block 1108the reselection-based prioritizer 330 obtains the list(s) (e.g.,neighbor cell list(s)) signaled by the network 100 that specify the setof carrier frequencies configured by the network 100 for measurement. Atblock 1110 the reselection-based prioritizer 330 determines whether thenetwork 100 has assigned cell reselection priorities to neighbor cellsincluded in the neighbor cell list(s) signaled to the mobile station125. If cell reselection priorities have been assigned by the network100, then at block 1115 the reselection-based prioritizer 330 uses thereselection priorities assigned to the neighbor cells and, thus, to thecarrier frequencies of the neighbor cells, to prioritize a subset offrequencies for which measurements are to be performed. For example, thereselection-based prioritizer 330 can prioritize the subset offrequencies to be those frequencies associated with neighbor cellshaving the highest reselection priorities. At block 1115, thereselection-based prioritizer 330 also limits the size of theprioritized subset of frequencies to be within the monitoringcapabilities of the mobile station 125. At block 1120, thereselection-based prioritizer 330 repeats reselection prioritizationprocessing for each RAT supported by the mobile station 125.

An example process 1200 that may be used to perform measurementlimitation signaling at block 620 of FIG. 6 and/or to implement theexample measurement limitation signaler 335 in the example mobilestation 125 of FIG. 3 is illustrated in FIG. 12A. An example companionprocess 1250 that may be used to process measurement limitationinformation received by the network element 220 of FIG. 2 and/or 5 isillustrated in FIG. 12B. With reference to the preceding figures andassociated descriptions, the process 1200 of FIG. 12A begins executionat block 1205 at which the measurement limitation signaler 335 beginsperforming measurement limitation signaling for each RAT supported bythe mobile station 125. For a particular RAT, at block 1208 themeasurement limitation signaler 335 obtains the list(s) (e.g., neighborcell list(s)) signaled by the network 100 that specify the set ofcarrier frequencies configured by the network 100 for measurement. Atblock 1210 the measurement limitation signaler 335 determines whetherthe monitoring capabilities of the mobile station 125 are exceeded bythe set of frequencies specified by the network 100 for measurement(e.g., via the signaled neighbor cell list(s)). If the monitoringcapabilities of the mobile station 125 are exceeded, then at block 1215the measurement limitation signaler 335 signals to the network 100 thatthe monitoring capabilities of the mobile station 125 are exceeded bythe set of frequencies currently specified for measurement by theneighbor cell list(s) signaled by the network 100. In some examples, themobile station 125 can also signal a prioritized list of frequencies tothe network 100, with the prioritized list of frequencies beingdetermined using one or more of the inter-frequency measurementprioritization techniques disclosed herein. Additionally oralternatively, the measurement limitation signaler 335 could sendlocation information to the network 100 indicating a location of themobile station 125. At block 1220, the measurement limitation signaler335 repeats measurement limitation signaling for each RAT supported bythe mobile station 125.

With reference to the preceding figures and associated descriptions, theprocess 1250 of FIG. 12B begins execution at block 1255 at which themeasurement limitation receiver 505 of the network element 220 receivesthe measurement limitation information from, for example, the mobilestation 125 indicating that the monitoring capabilities of the mobilestation 125 have been exceeded. At block 1260, the measurementlimitation receiver 505 stores the measurement limitation informationreceived from the mobile station 125 in the measurement informationdatabase 510 of the network element 220, including any prioritized listof frequencies suggested by the mobile station 125 to be configured formeasurement, any location information provided by the mobile station 125that can be associated with a particular prioritized list offrequencies, etc. At block 1265, the neighbor information signaler 515of the network element 220 processes the measurement informationdatabase 510 to update the set of frequencies included in the neighborcell list(s) signaled by the network element 220, as well as the orderin which frequencies appear in the list(s), to effect theprioritization(s) suggested by the mobile station 125. At block 1270,the neighbor information signaler 515 causes the network element 220 tosignal the updated neighbor cell list(s) in the appropriate cells of thenetwork 100.

An example process 1300 that may be used to perform carrier frequencyselection at block 620 of FIG. 6 and/or to implement the example carrierfrequency selector 340 in the example mobile station 125 of FIG. 3 isillustrated in FIG. 13. With reference to the preceding figures andassociated descriptions, the process 1300 of FIG. 13 begins execution atblock 1305 at which the carrier frequency selector 340 begins performingcarrier frequency selection processing for each RAT supported by themobile station 125. For a particular RAT, at block 1310 the carrierfrequency selector 340 obtains the set of frequencies configured by thenetwork 100 for measurement (e.g., via inclusion in one or more neighborcell list(s) signaled to the mobile station 125). At block 1315, thecarrier frequency selector 340 selects the first M frequencies listed inthe set of frequencies configured by the network 100 (M≧1). At block1320, the carrier frequency selector 340 prioritizes the subset offrequencies selected at block 1315 for measurement by the mobile station125. At block 1320, the carrier frequency selector 340 also limits thesize of the prioritized subset of frequencies to be within themonitoring capabilities of the mobile station 125. At block 1325, thecarrier frequency selector 340 repeats carrier frequency selection foreach RAT supported by the mobile station 125.

An example process 1400 that may be used to perform macro cellprioritization at block 620 of FIG. 6 and/or to implement the examplemacro cell prioritizer 345 in the example mobile station 125 of FIG. 3is illustrated in FIG. 14. With reference to the preceding figures andassociated descriptions, the process 1400 of FIG. 14 begins execution atblock 1405 at which the macro cell prioritizer 345 begins performingmacro cell prioritization for each RAT supported by the mobile station125. For a particular RAT, at block 1410 the macro cell prioritizer 345obtains the set of frequencies configured by the network 100 formeasurement (e.g., via inclusion in one or more neighbor list(s)signaled to the mobile station 125). At block 1415, the macro cellprioritizer 345 determines, as described above, a subset of theconfigured frequencies that are likely to be associated macro cells inthe mobile network 100. At block 1420, the macro cell prioritizer 345prioritizes the subset of frequencies determined at block 1415 formeasurement by the mobile station 125. At block 1420, the macro cellprioritizer 345 also limits the size of the prioritized subset offrequencies to be within the monitoring capabilities of the mobilestation 125. At block 1425, the macro cell prioritizer 345 repeats macrocell prioritization for each RAT supported by the mobile station 125.

As another example, the carrier frequency prioritization featuresdescribed with respect to corresponding FIGS. 3 and 8, may be enteredinto section 6.6.4 of the 3GPP TS 45.008 standard specification asfollows:

6.6.4 Measurements on Cells of other Radio Access Technologies

Insert the following text: “If the number of 3G (UTRAN FDD or UTRAN TDD)frequencies or cells in the 3G Cell Reselection list (see 3GPP TS44.018) exceeds the MS monitoring capabilities as defined above, the UEshall prioritise measurements of those 3G frequencies from the list thathave been most recently used by the UE (either camped on by the UE orused by the UE in CELL_DCH state).”

Additionally, the following optional text may be inserted: “For thispurpose, the MS shall maintain a list of the [5] UARFCNs that have beenrecently used (either camped on by the UE or used by the UE in CELL_DCHstate), excluding UARFCNs where the MS was only camped in limitedservice state. If the number of frequencies which are in the 3G CellReselection list, but which are not in the list of recently usedfrequencies, exceeds the MS monitoring capabilities, the MS shallmonitor frequencies according to i) the number of cells in the 3G CellReselection list on the frequency, ii) the most recent RSSI measurement,then by iii) MS implementation.”

The carrier frequency prioritization features described with respect tocorresponding FIGS. 3 and 8, may be entered into section 8.6.7.14 of the3GPP TS 25.331 standard specification as follows:

8.6.7.14 Inter-frequency Measurement

If the Inter-frequency cell info list, included in the variableCELL_INFO_LIST, includes a number (M) of frequencies that is larger thanthe number (N) considered in a UE performance requirement defined in[19] and [20]:

-   -   1> the UE shall:        -   2> prioritise the N frequencies most recently used by the UE            (either camped on by the UE or used in CELL_DCH state) and            meet the performance requirements on the (N) prioritised            frequencies.    -   1> the UE may:        -   2> ignore the remaining (M−N) frequencies.

As another example, the RSSI measurement-based prioritization featuresdescribed with respect corresponding FIGS. 3 and 10, may be entered intosection 6.6.4 of the 3GPP TS 45.008 standard specification as follows:

6.6.4 Measurements on Cells of Other Radio Access Technologies

Insert the following text: “If the number of 3G (UTRAN FDD or UTRAN TDD)frequencies or cells in the 3G Cell Reselection list (see 3GPP TS44.018) exceeds the MS monitoring capabilities as defined above, the MSshall perform UTRA Carrier RSSI measurements on all the listed 3G (UTRANFDD or UTRAN TDD, respectively) frequencies repeating these measurementsat least every TBDs [e.g. 60, 120s]. The UE shall perform RSCP and Ec/Iomeasurements on the 3 3G (UTRAN FDD or UTRAN TDD, respectively) UTRANfrequencies with the highest UTRA Carrier RSSI measurement.”

The RSSI measurement-based prioritization features described withrespect to corresponding FIGS. 3 and 10, may be entered into section8.6.7.14 of the 3GPP TS 25.331 standard specification as follows

8.6.7.14 Inter-Frequency Measurement

If the Inter-frequency cell info list, included in the variableCELL_INFO_LIST, includes a number (M) of frequencies that is larger thanthe number (N) considered in a UE performance requirement defined in[19] and [20]:

-   -   1> the UE shall:        -   2> perform UTRA Carrier RSSI measurements on the (M)            frequencies included in the variable CELL_INFO-LIST,            repeating these measurements at least every N s [e.g. where            N=60, 120 s];        -   2> perform measurements and meet this performance            requirement on the (N) frequencies with the highest UTRA            Carrier RSSI measurement.    -   1> the UE may:        -   2> ignore the remaining (M−N) frequencies

FIG. 15 is a block diagram of an example processing system 1500 capableof implementing the apparatus and methods disclosed herein. Theprocessing system 1500 can be, for example, a smartphone, a mobilephone, a personal digital assistant (PDA), a server, a personalcomputer, a network processing element, or any other type of computingdevice.

The system 1500 of the instant example includes a processor 1512 such asa general purpose programmable processor. The processor 1512 includes alocal memory 1514, and executes coded instructions 1516 present in thelocal memory 1514 and/or in another memory device. The processor 1512may execute, among other things, machine readable instructions toimplement the processes represented in FIGS. 6-14. The processor 1512may be any type of processing unit, such as one or more Intel®microprocessors from the Pentium® family, the Itanium® family and/or theXScale® family, one or more microcontrollers from the ARM® and/or PIC®families of microcontrollers, etc. Of course, other processors fromother families are also appropriate.

The processor 1512 is in communication with a main memory including avolatile memory 1518 and a non-volatile memory 1520 via a bus 1522. Thevolatile memory 1518 may be implemented by Static Random Access Memory(SRAM), Synchronous Dynamic Random Access Memory (SDRAM), Dynamic RandomAccess Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/orany other type of random access memory device. The non-volatile memory1520 may be implemented by flash memory and/or any other desired type ofmemory device. Access to the main memory 1518, 1520 is typicallycontrolled by a memory controller (not shown).

The processing system 1500 also includes an interface circuit 1524. Theinterface circuit 1524 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB),and/or a third generation input/output (3GIO) interface.

One or more input devices 1526 are connected to the interface circuit1524. The input device(s) 1526 permit a user to enter data and commandsinto the processor 1512. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball,an isopoint and/or a voice recognition system.

One or more output devices 1528 are also connected to the interfacecircuit 1524. The output devices 1528 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT)), by a printer and/or by speakers. The interface circuit1524, thus, typically includes a graphics driver card.

The interface circuit 1524 also includes a communication device such asa modem or network interface card to facilitate exchange of data withexternal computers via a network (e.g., an Ethernet connection, adigital subscriber line (DSL), a telephone line, coaxial cable, acellular telephone system, etc.).

The processing system 1500 also includes one or more mass storagedevices 1530 for storing machine readable instructions and data.Examples of such mass storage devices 1530 include floppy disk drives,hard drive disks, compact disk drives and digital versatile disk (DVD)drives. In some examples, the mass storage device 1530 may implement theconfiguration information storage 210, the neighbor database 320 and/orthe measurement information database 510. Additionally or alternatively,in some examples the volatile memory 1518 may implement theconfiguration information storage 210, the neighbor database 320 and/orthe measurement information database 510.

The coded instructions 1532 of FIGS. 6-14 may be stored in the massstorage device 1530, in the volatile memory 1518, in the non-volatilememory 1520, in the local memory 1514 and/or on a removable storagemedium, such as a CD or DVD 1532.

As an alternative to implementing the methods and/or apparatus describedherein in a system such as the processing system of FIG. 15, the methodsand or apparatus described herein may be embedded in a structure such asa processor and/or an ASIC (application specific integrated circuit).

Finally, although certain example methods, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the appended claims either literally or under the doctrine ofequivalents.

What is claimed is:
 1. A method in a mobile station, the methodcomprising: receiving, from a network, a list specifying a set offrequencies for which measurements are to be performed; and if the setof frequencies exceeds a monitoring capability of the mobile station,prioritizing measurement of a subset of frequencies from the set offrequencies based on information separate from the list obtained fromthe network, wherein the information includes a list of priorfrequencies used by the mobile station, and prioritizing measurement ofthe subset of frequencies comprises determining the subset offrequencies to be those frequencies included in both the list obtainedfrom the network and the list of prior frequencies used by the mobilestation.
 2. A method as defined in claim 1 wherein the list of priorfrequencies includes a list of frequencies most recently used by themobile station.
 3. A method as defined in claim 1 wherein the subset offrequencies is a first subset, and if measurement of the first subset offrequencies does not exceed the monitoring capability of the mobilestation, the method further comprises performing measurements for thefirst subset of frequencies and a second subset of frequencies from theset of frequencies, each frequency in the second subset of frequenciesbeing selected based on at least one of a number of cells associatedwith the frequency or a received signal strength indication associatedwith the frequency.
 4. A method as defined in claim 1 wherein the listof prior frequencies is maintained by the mobile station and includesfrequencies of a set of cells with which the mobile station has been ina connected state or on which the mobile station has been camped.
 5. Amethod as defined in claim 4 wherein the connected state corresponds toa CELL_DCH state.
 6. A method as defined in claim 4 wherein the list ofprior frequencies does not include any cell on which the mobile stationhas been camped in a limited service state.
 7. A method in a mobilestation, the method comprising: receiving, from a network, a listspecifying a set of frequencies for which measurements are to beperformed; and if the set of frequencies exceeds a monitoring capabilityof the mobile station, prioritizing measurement of a subset offrequencies from the set of frequencies based on information separatefrom the list obtained from the network, wherein prioritizingmeasurement of the subset of frequencies comprises determining thesubset of frequencies to include a first subset of frequencies appearingat the beginning of the list obtained from the network and a secondsubset of frequencies determined based on the information separate fromthe list obtained from the network.
 8. A method as defined in claim 7wherein the information includes received signal strength indicationmeasurements obtained for each frequency in the set of frequencies, andprioritizing measurement of the subset of frequencies comprisesdetermining the second subset of frequencies to include a first numberof frequencies having the highest received signal strength indicationmeasurements among the frequencies not included in the first subset offrequencies.
 9. A method as defined in claim 8 wherein the mobilestation is to measure the received signal strength indication for eachfrequency in the set of frequencies.
 10. A method as defined in claim 7wherein the information includes a respective reselection priorityobtained for each frequency in the set of frequencies.
 11. A mobilestation comprising: a memory to store a list specifying a set offrequencies for which measurements are to be performed, the list havingbeen received from a network; and a processor to prioritize measurementof a subset of frequencies from the set of frequencies based oninformation separate from the list obtained from the network if the setof frequencies exceeds a monitoring capability of the mobile station,wherein the information includes a list of prior frequencies used by themobile station, and the processor is to prioritize measurement of thesubset of frequencies by determining the subset of frequencies to bethose frequencies included in both the list obtained from the networkand the list of prior frequencies used by the mobile station.
 12. Amobile station as defined in claim 11 wherein the list of priorfrequencies includes a list of frequencies most recently used by themobile station.
 13. A mobile station as defined in claim 11 wherein thesubset of frequencies is a first subset, and if measurement of the firstsubset of frequencies does not exceed the monitoring capability of themobile station, the processor is to cause the mobile station to performmeasurements for the first subset of frequencies and a second subset offrequencies from the set of frequencies, each frequency in the secondsubset of frequencies being selected based on at least one of a numberof cells associated with the frequency or a received signal strengthindication associated with the frequency.
 14. A mobile station asdefined in claim 11 wherein the processor is to maintain the list ofprior frequencies, and the list of prior frequencies is to includefrequencies of a set of cells with which the mobile station has been ina connected state or on which the mobile station has been camped.
 15. Amobile station as defined in claim 14 wherein the connected statecorresponds to a CELL_DCH state.
 16. A mobile station as defined inclaim 14 wherein the list of prior frequencies does not include any cellon which the mobile station has been camped in a limited service state.17. A mobile station comprising: a memory to store a list specifying aset of frequencies for which measurements are to be performed, the listhaving been received from a network; and a processor to prioritizemeasurement of a subset of frequencies from the set of frequencies basedon information separate from the list obtained from the network if theset of frequencies exceeds a monitoring capability of the mobilestation, wherein the processor is to prioritize measurement of thesubset of frequencies by determining the subset of frequencies toinclude a first subset of frequencies appearing at the beginning of thelist obtained from the network and a second subset of frequenciesdetermined based on the information separate from the list obtained fromthe network.
 18. A mobile station as defined in claim 17 wherein theinformation includes received signal strength indication measurementsobtained for each frequency in the set of frequencies, and the processoris to prioritize measurement of the subset of frequencies by determiningthe second subset of frequencies to include a first number offrequencies having the highest received signal strength indicationmeasurements among the frequencies not included in the first subset offrequencies.
 19. A mobile station as defined in claim 18 wherein themobile station is to measure the received signal strength indication foreach frequency in the set of frequencies.
 20. A mobile station asdefined in claim 17 wherein the information includes a respective cellreselection priority obtained for each frequency in the set offrequencies.